Why should they?
This is the problem with how a lot of people think, if one Muslim says or does something then certain people will tar them all with the same brush.
Have you ever apologised when some white Christian or Catholic has committed murder or abused a child?
Christians have a hierarchy, if something goes wrong then the head of the church apologises publicly.
That's why people end up thinking muslims either don't give a stuff or secretly agree with the situation.
Mohammed didn't anticipate the social media requirement to publicly apologise for his violent death cult, but when you can just behead all of your critics then I can see why he didn't think the issue was worth considering.

